4. properties of_formaldehyde

Formaldehyde 2014
B.TECH Project – IIT (BHU) Varanasi Page 1
CONTENTS
1. Acknowledgement
2. Summary
3. Introduction
4. Properties of Formaldehyde
 Physical properties
 Chemical properties
 Method of analysis
5. Manufacturers and economics
6. Usage and applications
7. Different processes for the manufacture of Formaldehyde
 Silver Catalyst process
 Oxide process
 Reason for choosing silver process
8. The Silver process
 Process description
 Controlling Parameters
 Equipment description
 Stream description
9. Material Balance
 General information
 Material balance around different equipments
 Overall material balance
10.Energy Balance
 Air preheater
 Energy balance around methanol before evaporation
 Methanol Evaporator.
 Reactor effluent gases cooling

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11.Process design
 Reactor
 Absorption Column
 Process design of few other equipments
12.Mechanical Design
 Reactor
 Absorption Column
13.Process utilities
14.Control and Instrumentation
15.Plant Safety
16.Effluent Treatment
 Design of Deionizer
17.Plant location and layout
 Plant location
 Plant layout
18.Plant Economics
19.Bibliography
20.Bibliography
21.Nomenclature

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ACKNOWLEDGEMENT
This project is the result of the continuous guidance and encouragement of the
teachers of The Department of Chemical Engineering and Technology, IIT-BHU.
I express my deep sense of gratitude and reverence to Prof. A.S.K. Sinha, Head of
Department, Department of Chemical Engineering and Prof. P. Ahuja, Prof. KK
Singh, Dr. VL Yadav and Dr. Pradeep Kumar, Project Coordinators, for providing
us the opportunity to work in this project, for their scrupulous supervision and
being available for us to sort out any kind of trouble in the way.
It is my privilege to express indebtedness and deep sense of gratitude to all the
respected teachers of our department for their guidance throughout the duration
of the project. I also extend my gratitude to the library staff for their co-
operation.
Finally, I would like to thank all my batch-mates for their unalloyed helping hands
which provided us with both material and moral support throughout the project.
Date: _____________ _______________
Shivam Singh
10102EN067
B.Tech. Part-IV

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SUMMARY OF THE PROJECT
The main objective of this project is to conduct a comprehensive study, from a
chemical point of view, that would ultimately lead to an integrated design of a
plant that produces 50 TDP of Formaldehyde.
During this study we will consider many aspects including the entire plant‟s process
unit design, process flow diagrams, cost estimations, operation parameters,
equipment sizing, construction materials and environment/safety precautions.
This project requires the theoretical and practical application of mass transfer,
heat transfer, fluid dynamics, unit operations, reaction kinetics and process
control. There are several tasks that are crucial to the completion of the project
outlines including mass and energy balances, design of the reactor, design of heat
exchangers, design of the absorber and distillation column, energy optimization,
economic analysis and hazard analysis.
Formaldehyde (CH2O), the target product of the project‟s plant, is an organic
compound representing the simplest form of the aldehydes. It acts as a synthesis
baseline for many other chemical compounds including phenol formaldehyde, urea
formaldehyde and melamine resin. The most widely produced grade is formalin (37
wt. % formaldehyde in water) aqueous solution.
In this project‟s study, formaldehyde is to be produced through a catalytic vapour-
phase oxidation reaction involving methanol and oxygen according to the following
reactions:
CH3OH + 1/2O2 → HCHO + H2O (1)
CH3OH → HCHO +H2 (2)
First reaction is desirable which is exothermic with a selectivity of 9, while the
second is an endothermic reaction. The project‟s target is to design a plant with a
capacity of 50Tons/day. This plant is to include three major units; a reactor, an
absorber and a distillation column. Also it includes pumps, compressors and heat
exchangers. All are to be designed and operated according to this production
capacity.

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PROBLEM INFORMATION
Formaldehyde is to be commercially manufactured on an industrial scale from
methanol and air in the presence of a sliver catalyst or the use of a metal oxide
catalyst. The former of these two gives a complete reaction of oxygen. However
the second type of catalyst achieves almost complete methanol conversion. The
silver catalyzed reactions are operated at atmospheric pressure and very high
temperatures (600o
C – 650o
C) presented by the two simultaneous reactions above
(1) and (2).
The standard enthalpies of these two reactions are ΔHo
1 = -156 KJ and ΔHo
2 = 85
KJ respectively. The first exothermic reaction produces around 50 % -- 60 % of the
total formed formaldehyde. The rest is formed by the second endothermic
reaction.
These reactions are usually accompanied by some undesired by-products such as
Carbon Monoxide (CO), Carbon Dioxide (CO2), Methyl Formate (C2H4O2) and Formic
Acid (CH2O2). Below is table of these side reactions that may take place in the
process:

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The reactor in this project‟s problem is to receive two streams; the first is a
mixture of fresh methanol and recycled methanol. The second stream to the
reactor mixed with the first is compressed fresh air.
The absorber receives the reactor‟s outlet and afresh stream of water. Absorption
of 99% is expected. The distillation column receives the liquid then separates the
overhead methanol stream then recycles it back to methanol fresh feed mixing
point.
The bottom formaldehyde stream is pumped and mixed with deionized water
forming (37 wt. % formaldehyde) formalin stream which sent for storage. The
mixing is presented as follows:
The catalyst to be implemented in the reactor‟s design is silver wired gauze layers
or catalyst bed of silver crystals. The catalyst is spherical with 1mm diameter and
a void fraction or porosity of 0.5. The common design of the silver catalyst is a thin
shallow catalyzing bed with a thickness of 10 to 55 mm.
The usual life span of this catalyst is three to eight months, where the silver can
be recovered. The purity of the feed flow rates is very crucial due to the fact that
the catalyst is very receptive to poisoning that would kill the reaction and reduces
the production to zero if traces of sulfur or a transition metal are present.

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PHYSICAL & CHEMICAL PROPERTIES
This section includes all the major participating materials to the production plant.
These properties are based upon operating conditions of the plant‟s design:
INITIAL BLOCK FLOW DIAGRAM

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LITERATURE REVIEW OF PRODUCTION PROCESS
Formaldehyde was discovered in 1859 by a Russian chemist named Aleksandr
Butlerov. Then in 1869, it was ultimately identified by the German chemist August
Hofmann. The manufacture of formaldehyde started in the beginnings of the
twentieth century. Between 1958 and 1968, the annual growth rate for
formaldehyde production averaged to 11.7%.
In the mid-1970s, the production was 54% of capacity. Annual growth rate of
formaldehyde was 2.7% per year from 1988 to 1997. In 1992, formaldehyde ranked
22nd among the top 50 chemicals produced in the United States. The total annual
formaldehyde capacity in 1998 was estimated by 11.3 billion pounds. Since then
and the production capacity around the globe is expanding exponentially reaching
a world‟s production of 32.5 million metric tons by 2012.
Due to its relatively low costs compared to other materials, and its receptivity for
reaching high purities, formaldehyde is considered one of the most widely
demanded and manufactured materials in the world. It is also the centre of many
chemical researches and alternative manufacture methods.
This also explains the vast number of applications of this material including a
building block for other organic compounds. Formaldehyde is a very versatile
chemical and it is used in many industries, including -
 Antiseptic, Germicide and Fungicide
 Purifier in Sugar Industry
 Leather Tanning
 Photograph Washing
 Wood Working
 Cabinet Making Industries
 Glues and Adhesives
 Paints
 Explosives
 Tissue Preservation
One of the main use of Formaldehyde is formaldehyde based resins. Most of the
formaldehyde produced in the world is used for this. Different resins are made
from formaldehyde using different substrates. One of the most popular is Urea-
Formaldehyde resin. Its major use is as adhesives and it is also used as a binder for
glass fibre roofing materials. We will now discuss the various productions methods
available.

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DIFFERENT PROCESSES FOR MANUFACTURE
In general two types of processes are used today.
THE SILVER CATALYST PROCESS
This process is based on partial oxidation and reduction process at 600 °C on silver
grains, works with the excess of methanol above the upper explosion limit of the
mixture methanol-air.
In this process, formaldehyde is formed both by oxidation and by dehydrogenation
reactions:
CH3OH + 1/2O2 → HCHO + H2O + 37 KCal/g-mol
CH3OH → HCHO+H -20.3 KCal/g-mol
.
The other minor reactions that are taking place are:
CH3OH+ O2 → CO + 2 H2O -162 KCal/g-mol
H2 + ½ O2 → H2O -241.82 KJ/g-mol
HCHO+ ½ O2 → CO + H2O -563.46 KJ/g-mol
HCHO → CO + H2
The reaction occurs over a silver catalyst at typical conditions of (560-
620o
C) and pressure slightly over atmosphere. Methanol conversion is 65- 75
% per pass.
THE OXIDE PROCESS
This process is based on the air oxidation of the methanol under “Lean”, i.e. low
methanol concentration, conditions to avoid the explosive range.
In this process the methanol is produced only by the oxidation reaction:

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A small portion of formaldehyde gets oxidized further:
HCHO+1/2O2 → CO + H2O -563.46 KJ/g-mol
The reactions occur over a mixed oxide catalyst containing molybdenum oxide and
iron oxide in the ratio 1.5 to 3. The reaction temperature is around 550o
F and the
reaction is slightly over atmospheric pressure. An excess air is used to ensure a
near complete and to avoid the explosive range for methanol.
Fresh methanol is mixed with air plus recycled gas in a steam-heated vaporizer.
The effluent from this device is fed to the reactor, which is of the vertical packed-
tubular type. The reacting gas mixture flows downward through the tubes and
transfers its heat of reaction to a circulating heat transfer medium on the shell
side of the reactor.
The heat transfer medium in turn vaporizes the feed water to produce steam at
pressures up to about 25 atmosphere .The catalyst is granular or spherical
supported Fe/Mo and has aging characteristics such that over the period of its life
(12-15 months) the bed temperature must be increased from about 450 – 550 o
F.
The exit gases from the reactor pass through a heat recovery exchanger, where
low pressure steam is generated, and thence to the absorption column where
water is used as the scrubber column.
The absorber can be either of the packed or the tray type. The top of the absorber
is kept at a low temperature in order to ensure adequate removal of formaldehyde
from the overhead gases. The bottom stream from the absorber represents the
final product. Because the reaction conditions promote more formic acid than do
those for the silver process, it is necessary to remove this acid by ion exchange
method.
A large portion of the absorber overhead is recycled back to the feed system. This
permits the methanol content of the reactor feed to be as high as 9.0 volume%
and causes a dilution of the gas from the absorber to the point that is not always
necessary to provide further treatment of the gas discharged from the system. For
this reason, the absorption column in this process is higher than that foe silver
catalyst process.

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REASON FOR CHOOSING SILVER CATALYST PROCESS
Studies of the two processes based on the nominal size of 100,000,000 lb/yr of 37%
formaldehyde solution showed that the silver process was far economical than the
oxide process. It was found that the capital cost of the silver process was about
20% lower than the oxide process with manufacturing cost essentially the same.
The conversion of methanol to formaldehyde in the improved silver process is
normally between 77% and 95%, while in the older it is about 55%. So, conversion is
also not a problem anymore.
The most radical improvements in the silver catalyst process have been made by
BASF and are now used commercially. A different form of the catalyst, a higher
reaction temperature, and changes in reactor feed composition have made
possible a high methanol conversion; thus, it is no longer necessary to recover
unreacted methanol. Maximum size of a production unit has also been increased by
these changes.
PROCESS DESCRIPTION OF SILVER CATALYST PROCESS
This process is based on partial oxidation and reduction process at 600 °C on silver
grains, works with the excess of methanol above the upper explosion limit of the
mixture methanol-air.
In this process, formaldehyde is formed both by oxidation and by dehydrogenation
reactions:
CH3OH → HCHO + H2 -20.3 KCal/g-mol
The other minor reactions that are taking place are:
CH3OH + O2 → CO + 2 H2O -162 KCal/g-mol
H2 + ½ O2 → H2O -241.82 KJ/g-mol
HCHO+ ½ O2 → CO + H2O -563.46 KJ/g-mol
HCHO → CO + H2

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The reaction occurs over a silver catalyst at typical conditions of (560-620o
C) and
pressure slightly over atmosphere. Methanol conversion is 65- 75 % per pass. Since
the reactor feed is kept on the rich side of the explosive limit, all the oxygen is
converted .Unreacted methanol is separated from the reaction mixture and
recycled.
A flow diagram is shown. Fresh Methanol, which must be free from iron carbonyls
and sulphur compounds (catalyst poison), is combined with recycle methanol and
pumped through a steam-heated vaporizer. An additional heat exchanger for super
heating the methanol may also be used. Air is drawn through a filter and
compressed in a blower for feed to the process. An air washer is provided for
removal of possible catalyst poisons, and while water is usually sufficient for the
scrubbing liquid, caustic solutions are sometimes needed. The washed air is pre
heated and mixed with fresh feed methanol to give a combined feed temp. of
about 150o
C. Provision is made for the addition of up to 0.75 lb steam /lb
methanol to serve as thermal ballast for reaction control.
The converter consists of a feed distribution chamber, a shallow bed of catalyst,
and a waste heat boiler. The catalyst is in the form of silver crystals or gauge and
the catalyst bed typically is 0.5-1.0 in deep and up to 6-7 ft. in diameter. To avoid
undesirable reactions it is necessary to quench the reaction product in less than
about 0.02 s.
Quenching is accomplished in a directly connected shell-and-tube heat exchanger
where the net exothermic heat of reaction is used to generate steam. Typically
the catalyst is contained in a basket resting on top of the waste heat boiler upper
tube sheet, and the gases flow downward through the tubes. These gases then pass
to the absorber where formaldehyde and methanol are recovered from bottom
liquid.
The absorber typically comprises two absorption/cooling sections with
recirculating liquid (thus providing a maximum of two theoretical stages). Either
packing or trays can be used for the absorber column. the heat of solution and the
residual sensible heat in the gases is removed by heat exchangers. Uncondensed
material from the circulating sections flows upward through a water contracting
zone for further absorption and finally leaves the top of the column and flows to a
suitable device for removing residual organics and carbon monoxide. Since the
gases have heating value, it is usually appropriate to add it to the fuel used for
steam generation boilers.
The absorber bottoms stream is pumped to the still where methanol is separated
overhead and the product formaldehyde solution is the bottom stream. The water
content of the bottoms is controlled by the amount of makeup water added at the

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top of the absorption column, and thuds there are definite upper limit for the
water content in the bottoms.
The methanol still typically is a tray column with conventional refluxing and re-
boiling. For reduction of the bottom to 1.0 wt% methanol, 40 bubble cap trays are
used. Residence time distribution can depend on the shifting equilibrium
composition of the liquid, and the controlled residence time characteristics of the
bubble cap tray appear advantageous. The methanol net distillate is recycled back
to the fresh feed of methanol. The recycle is done in vapor phase to conserve
energy. Also, some design employs vacuum distillation of methanol still to
discourage the formation of higher products like acetaldehyde.
If the formic acid content is higher then the distillate bottom is passed through
deionizer. Also a certain amount of product is left in distillation column for
stabilization.

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LIST OF EQUIPMENTS
The production plant contains following equipment –
 One (1) evaporator
 One (1) air blowers (one with speed variator)
 One (1) reactor with boiler tubes
 One (1) gas/gas heat exchanger
 Seven (7) liquid/liquid heat exchangers
 One (1) condensers
 One (1) packing absorption column
 Two (2) tray absorption columns (bubble caps)
 One (1) tray distillation column (bubble caps)
 Vessels
 Pumps (Sihi) doubled to secure the process
 Pipes, valves, etc.
 Steel : SS 316 L
 Protection of electric motors : IP 55 Eexd II BT 4
CONTROLLING PARAMETERS:
1. Composition of the feed entering the evaporator: It is controlled by means
of automatic valves that control the inflow rate of methanol & water. The
composition is kept maintained at 64% methanol as it is crucial in deciding
the composition of the feed entering the reactor.
2. Temperature of the evaporator. It is kept around 70-72C by controlling the
rate of steam applied in the outer jacket. A temperature gage on the
evaporator indicates temperature continuously. It is important as it decides
the amount of methanol evaporating & thus the composition of the feed to
the reactor.

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3. Pressure of the evaporator. Maintained at ~ 900 mm wc & monitored by
means of pressure gage.
4. Level of the mixture in the evaporator. Maintained at 45% of total capacity
& monitored by a level indicator outside the evaporator. It is important as it
decides the rate of evaporation of the mixture & thus affects the yield.
5. Composition of the feed entering the reactor. Maintained at 80% methanol &
controlled indirectly by controlling the composition of the feed entering the
evaporator. It is important as it controls the composition of formaldehyde
formed.
6. Phase of the feed entering the reactor. No liquid should enter the reactor
dome as it could spoil the silver bed. To ensure this feed is passed through
superheater before it enters the reactor so that no condensation takes
place. In addition to this another separator is employed just before the feed
enters the reactor which filters out any liquid & send it back to the
evaporator.
7. Temperature & pressure inside the reactor. The temperature should be
maintained at 680-700C. This is important as the reaction conditions affect
the yield.
8. Composition of the formaldehyde leaving the absorption column. It is
maintained at 37% formaldehyde by means of controlling the flow rate of
the D.M. water added from the top of absorption column.
9. Other gases present should be removed.
10. Specific gravity of formaldehyde :The specific gravity of formaldehyde is
1.12.
INFLUENCE OF REACTION TEMPERATURE
Conversions and yields vary as a function of temperature. A light-off temperature
was observed at about 570 K. CO2 displayed a maximal yield at the relatively low
temperature of 575 K and then dropped off with temperature. The yield of

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formaldehyde increased gradually with temperature and reached a maximum at
about 923 K, which corresponds well with the commercial operation temperature.
The abrupt decrease of the formaldehyde yield above 923 K was accompanied by a
yield increase of CO and H2, suggesting a gas phase decomposition of formaldehyde
to CO and H2 at the high temperature. Formic acid appeared only in a limited
temperature region (approximately 570–850 K) and could not be observed in the
high temperature region before the deactivation of catalyst
INFLUENCE OF RESIDENCE TIME
Methanol conversion and the selectivity to formaldehyde and hydrogen were
determined at different residence times (0.06–0.45 s). The higher the residence
time was, the more methanol was converted.
However, the longer residence time was not beneficial for the formaldehyde
formation: its selectivity decreased apparently under the longer residence time,
which may be partly due to the fast decomposition of formaldehyde in the gas
phase to H2 and CO at high operation temperatures. The H2 selectivity did increase
with residence time, albeit not to the extent that the formaldehyde selectivity
decreased.
INFLUENCE OF MOLAR RATIO OF H2O / CH3OH IN THE FEED
The influence of water vapor in the reaction gas on the formaldehyde selectivity
was estimated. Water vapor content was varied in the region of H2O/CH3OH molar
ratio of 0–2.0. The space velocity was kept constant by varying the N2 flow
accordingly. This led to a constant CH3OH/O2 molar ratio. Each result was an
average over a 15 h lasting stationary test.
The conversion of methanol increased with the H2O/CH3OH molar ratio, however,
the selectivity to formaldehyde passed through a maximum around a H2O/CH3OH
molar ratio of about 0.75, which corresponds basically well with the above-
mentioned molar ratio of 0.67 in industrial formaldehyde manufacture (indicated
by the vertical dashed line). Because of the experimental error in the
formaldehyde detection, the experiment was reproduced at different feed
concentrations, supporting the conclusions reported above.
It is also show that the selectivity to CO2 decreased with the molar ratio of
H2O/CH3OH. The more water vapor was fed in the reaction gas, the less CO2 was
detected.

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SAFETY & ENVIRONMENT PRECAUTIONS
The main concern is mainly with precautions and protocols that are to be followed
while handling materials in the plant. Safety equipment includes: splash goggles,
protective coats, gloves and safety shoes are all required in dealing with these
materials regardless of the their reactivity and stability. These documentations
will include the two target materials and compounds encountered and utilized in
the plant as follows:
METHANOL
 It‟s a light, volatile, colorless, clear and flammable liquid. It has a
distinctive sweetish smell and close to alcohol in odor and colorlessness.
Methanol is very toxic to humans if ingested. Permanent blindness is caused
if as little as 10 mL of methanol is received and 30 mL could cause death.
Even slight contact with the skin causes irritation.

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EXPOSORE
 Exposure to methanol can be treated fast and efficiently. If the contact was
to the eyes or skin, flushing with water for 15 minutes would be the first
course of action. Contaminated clothing or shoes are to be removed
immediately. If the contact is much more series, use disinfectant soap, then
the contaminated skin is covered in anti-bacteria cream. Inhalation of
methanol is much more hazardous than mere contact. If breathing is
difficult, oxygen is given, if not breathing at all artificial respiration
REACTIVITY
 Methanol has an explosive nature in its vapor form when in contact with
heat of fires. In the case of a fire, small ones are put out with chemical
powder only. Large fires are extinguished with alcohol foam. Due to its low
flash point, it forms an explosive mixture with air. Reaction of methanol and
Chloroform + sodium methoxide and diethyl zinc creates an explosive
mixture. It boils violently and explodes.
STORAGE
 The material should be stored in cooled well-ventilated isolated areas. All
sources of ignition are to be avoided in storage areas.
FORMALIN( FORMALDEHYDE 37 WT% SOLUTION)

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 This material is a highly toxic material that the ingestion of 30 ml is
reported to cause fatal accidents to adult victims. Formaldehyde ranges
from being toxic, allergenic, and carcinogenic. The occupational exposure
to formaldehyde has side effects that are dependent upon the composition
and the phase of the material. These side effects range from headaches,
watery eyes, sore throat, difficulty in breathing, poisoning and in some
extreme cases cancerous. According to the International Agency for
Research on Cancer (IARC) and the US National Toxicology Program: „‟known
to be a human carcinogen‟‟, in the case of pure formaldehyde.
FIRE HAZARDS
 Formaldehyde is flammable in the presence of sparks or open flames.
EXPOSURE
 Exposure to methanol can be treated fast and efficiently. If the contact was
to the eyes or skin, flushing with water for 15 minutes would be the first
course of action. If the contact is much more series, use disinfectant soap,
then the contaminated skin is covered in anti-bacteria cream. Inhalation of
methanol is much more hazardous than mere contact. The inhalator should
be taken to a fresh air.
STORAGE AND HALDLING
 Pure Formaldehyde is not stable, and concentrations of other materials
increase over time including formic acid and para formaldehyde solids. The
formic acid builds in the pure compound at a rate of 15.5 – 3 ppm/d at 30
oC, and at rate of 10 – 20 ppm/d at 65 oC. Formaldehyde is best stored at
lower temperatures to decrease the contamination levels that could affect
the product‟s quality. Stabilizers for formaldehyde product include
hydroxypropylmethylcellulose, Methyl cellulose, ethyl cellulose, and poly
(vinyl alcohols).

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MATERIAL BALANCE
In this section, material balance over some important units has been performed
manually. The final stream tables give the composition in all streams.
Equation used
Inlet – outlet + generation – consumption = accumulation
as accumulation = 0
equation given above can be applied for mass balance.
MASS BALANCE FOR REACTOR:
Main reactions in reactor are -
CH3 OH + ½ O2 = HCHO + H2O ……….(1)
CH3 OH = HCHO + H2 ……….(2)
CH3 OH + O2 = CO + 2H2O ……….(3)
ASSUMPTIONS
 Total molar conversion of methanol is 81%.
 60% of formaldehyde is formed via reaction 1 and remainder is formed
by reaction 2.
 Conversion values for reaction 1 and 2 are obtained by using literature
survey on the formaldehyde production process.
Formaldehyde produced = 50 TPD
= (50*1000)/30 = 1666.66 Kmol/day
= 69.44 Kmol/hr (approx. 70 Kmol/hr)
From reaction 1, formaldehyde produced = (0.6*70) Kmol/hr = 42 Kmol/hr
From reaction 2, formaldehyde produced = (0.4*70) Kmol/hr = 28 Kmol/hr
By stoichiometry, kmols of methanol converted = 42+28= 70 Kmol/hr
Now, 1% of methanol total is consumed in reaction 3.
So, total methanol taken in feed stream = (70*100)/80 = 87.5 Kmol/hr
Since,the ratio of methanol to oxygen for this process in industrial reactors is 2.5.
Amount of oxygen required = 87.5/2.5 = 35 Kmol/hr

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Hence,nitrogen in feed stream = 140 Kmol/hr
Amount of methanol consumed in reaction 3 = 87.5/100 = 0.875 Kmol/hr
Total amount of water produced in reaction 1&3 = (2*0.875)+42 = 43.75 Kmol/hr
Hydrogen in exit stream = 28 Kmol/hr
Carbon monoxide in exit stream = 0.875 Kmol/hr
Amount of oxygen consumed in reaction 1&3 = (0.5*42)+0.875 = 21.875 Kmol/hr
Oxygen remaining = 35-21.875 = 13.125 Kmol/hr
Unreacted methanol = 87.5-70-.875 = 16.625 Kmol/hr
REACTOR
Components Stream 9
(kmol/hr)
Stream 10
(kmol/hr)
Methanol 87.5 16.625
Formaldehyde - 70
Water - 43.75
Oxygen 35 13.125
Nitrogen 140 140
Hydrogen - 28
Carbon monoxide - 0.875
MASS BALANCE FOR ABSORBER:
As more than 90% formaldehyde is absorbed in absorption column
In inlet stream, amount of formaldehyde = 70 Kmol/hr
Fresh water is added in stream 12 = 70 Kmol/hr (approx.)
Assuming 99.9% formaldehyde is absorbed
Amount of formaldehyde in stream 14 =69.93 Kmol/hr
Methanol in exit stream = 16.625 Kmol/hr

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FORMALIN ABSORBER
Components Stream 11
(kmol/hr)
Stream 12
(kmol/hr)
Stream 13
(kmol/hr)
Stream 14
(kmol/hr)
Methanol 16.625 - 0.09 16.625
Formaldehyde 70 - 0.07 69.93
Water 43.75 70 0.5 113.75
Oxygen 13.125 - 13.120 0.005
Nitrogen 140 - 139.5 0.5
Hydrogen 28 - 27.95 0.05
Carbon monoxide 0.875 - 0.879 0.001
FORMALIN DISTILLATION COLUMN
Components Stream 15
(kmol/hr)
Stream 16
(kmol/hr)
Stream 17
(kmol/hr)
Methanol 16.625 16.620 0.005
Formaldehyde 69.93 0.03 69.90
Water 113.75 7.915 105.33
Oxygen 0.005 0.005 -
Nitrogen 0.5 0.5 -
Hydrogen 0.05 0.05 -
Carbon monoxide 0.001 0.001 -

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REACTOR
The reactor used in the formaldehyde plant utilizes catalyst bed and has the shell
and tube heat exchanger located in it. The catalyst bed actually lies on the shell
and tube heat exchanger. The reaction takes place on the exchanger and as can be
seen from the rate equation is actually very fast. So, the diffusion or mass transfer
resistance is not considered in the reaction.
The use is made of rate equation in terms of moles of methanol consumed.
The reactor is made up of copper material and it is about 0.992 m in diameter. It
consists of a silver bed in the form of granules weighing about 25 kg. The silver bed
has the following layers:
6 copper screens and two silver screens at bottom. 1 silver screen is kept at top.
The temperature of the catalyst bed is maintained at about 600C. The heat
evolved from the highly exothermic reaction raises the temperature to 670-700C.
Also initially passing steam in the outer jacket raises the temperature. Air required
for the reaction is provided from the air valve provided near the reactor.
Here, the methanol vapours are converted into formaldehyde by an oxidation
reaction in the presence of silver catalyst.
The methanol vapours enter the reactor dome at a temperature of about 120C.
The methanol vapours are then converted into vapours of HCHO in the reactor in
the presence of high-pressure air and the high temperature of about 700C. The
vapours go down into the steam generator and then to the condenser.

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REACTOR HEAT CALCULATIONS
I Method.
Using Heat Of Reactions for different Reactions
Reaction No. Nature Moles Reacted Heat Of Reaction Heat
1 Exothermic 8.559 37.3
1335.74
5
2 Endothermc 5.706 20.3
484.640
3
3 Exothermic 1.538 162
1042.46
9
4 Exothermic
5 Exothermic 0.14 51
29.8737
6
6 Exothermic 0.14
II Method.
Using Heat Of Reaction Cumulatively
heat of
reaction 116.6 Kj/Kmol
heat released
1663.29
9 Kj/sec
HEAT BALANCE FOR REACTOR EFFLUENT GASE
Species Moles of Diff. Species Fraction
CH3OH 0.61
0.09610
8
HCHO 1
0.15755
5
H2 0.418
0.06585
8
CO2 0.22
0.03466
2
CO 0.13
0.02048
2
H2O 0.842
0.13266
1
O2 0.009
0.00141
8
N2 3.118
0.49125
6
Total 6.347
Formulae Of Specific Heat
Used
Specific Heat = a+b*T+c*T
2
+c*T
3
+d*T
4
Constants CH3OH HCHO H2 CO2 CO H2O O2
a 21.37 3.094 28.9105 21.3655 29.0277 32.4721 23.3768
b 0.070843
0.00387
7 0.00102
0.06428
1 -0.00282
7.96E-
05 -0.00406
c 0.00002586 -3.1E-06 -1.476E-07 -4.1E-05 1.16E- 1.32E- 1.04E-

Formaldehyde 2014
05 05 05
d -2.8497E-08
1.01E-
09 7.69E-10 9.8E-09 -4.7E-09 -4.5E-09 -3.9E-09
After Multiplying With
Fractions
Constants CH3OH HCHO H2 CO2 CO H2O O2
a 2.053657
0.48761
4 1.908093
0.74779
3
0.58055
4
4.31878
9
0.02337
7
b
0.00680801
2
0.00061
1
0.0000673
2 0.00225 -5.6E-05
1.06E-
05 -4.1E-06
c
2.48515E-
06 -4.9E-07
-9.7416E-
09 -1.4E-06
2.33E-
07
1.76E-
06
1.04E-
08
d
-2.73856E-
09
1.58E-
10
5.0754E-
11
3.43E-
10 -9.4E-11 -6E-10 -3.9E-12
Constants Total Heat
a 24.6490089
5003.74
9
b
0.00716214
6
791.846
1
c
9.02241E-
06
549.567
2
d
-5.32758E-
09 -180.783
Temperature Specifications of Inlet and Outlet reactor effluent gases
Inlet
Temperature deg. C 373 in K 646.13
Outlet
Temperature deg. C 170 in K 443.13
Energy Calculations
Heat Required
(Sp.
Heat.* KJ/Kmol
6164.37
9
Flow Rate of
Gases Moles/sec
90.5399
6
Heat Required
(flow Rate*Sp.
Heat.* KW
558.122
6
Cooling Medium is Water
Inlet Temperature of Water deg. C 25 in K 298.13
Outlet Temperature of Steam deg. C 204.44 in K 477.57
Specific Heat Of Water KJ/KgK 4.184
Total Heat To Be Quenched KW
2221.42
2
(Total heat is equal to latent heat and sensible heat)

Formaldehyde 2014
Steam
Enthalpy Btu/lb 826
Steam
Enthalpy KJ/Kg
1920.00
6
Flow Rate of Water is calculated by dividing the heat load by the temp. difference of
water and
the specific heat of water
Flow Rate of
Water Kg/sec
0.83174
9
Catalyst Calculations
Reaction Rate mole/Kg catalyst hr. K1*Pm/(1+K2Pm)
where K1& K2 are constants
P stands for pressure in atm.
m stands for methanol
Consatnts K1 K2
a 8.52 3810
b 10.79 7040
Temp. of Reaction in deg. C= 600 in K = 873.13
Consatnts log K1 2.727054 K1 533.4013
log K2 4.156389 K2 14334.7
Moles of Methanol Reacted
taking conversion into consideration for 1 mol formaldehyde
moles 1.13
Moles of Methanol Reacted taking conversion into consideration /hr
moles/hr 58030.02
Mole fraction of Meyhanol in gases coming to reactor
Moles of Methanol 0.644
Total Moles of Gase 1.487
fraction 0.433087
Reactor

Formaldehyde 2014
Conditions
Temp. 873.13 K
Pressure 1.1 atm
Partial Press. Of Methanol 0.476395
Amount of Catalyst Required Kg 25.32358
TABLE 7: SHELL DIA CORRELATION DATA FOR DIFFERENT ALLOYS

Formaldehyde 2014
HEIGHT AND DIAMETER
For the gases
Inlet Temperature in deg. C = 373 in K = 646.13
Outlet Temperature in deg. C = 170 in K = 443.13
For the water
Inlet Temperature in deg. C = 25 in K = 298.13
Outlet Temperature in deg. C = 204.44 in K = 477.57
Boiling Point in deg. C = 204.44 in K = 477.57
Total Heat to be Removed KW 2221.421577
Area Calculation
LMTD deg. C 358.05
R 1.39
S 0.318
Correction Factor (from graph) 0.92
Corrected LMTD 329.406
Taking U equals to W/m^2 deg. C 500
Area Outside
Reqd. m
2
13.48743846
Tuibes Used are 20 mm OD 16 mm ID and 4.88 m length
Area of One tube m
2
0.303
Number of Tubes 44.51299822 or 46
Triangular Pitch (1.25*OD) mm 25
Bend Radius (3*OD) mm 60
Tube Out Limit Dia. mm 495.3846154
Heat Flux (based on estimate area) KW/m^2 164.703
hnb W/m^2 25873
Heat Transfer Coeff. Calculation
Air Mixture Condensing Coeff. Is taken as 400 W/m^2
1/hnb 3.86503E-05
1/fouling factor for reactor gases 0.0001
1/heat transfer coeff. For tube wall 4.05716E-05
For Steam Side 0.0015625
1/Uo 0.001741722
Uo 574.1444765
Uo cimes out too close to assumed from value of 500 and higher so is in safe side

Formaldehyde 2014
Max. Allowable Heat Flux
surface Tension N/m 0.0352
Liq. density Kg/m^3 960
Vap. Density Kg/m^3 7.725
Number of Tubes 184
For square arrangement, Kb 0.41
Heat Flux 2055.62
Factor 0.7
Actual Max. Flux 1438.934
So, Its safe
Tube Sheet Layout, Bundle Dia., Db mm 496
Taking shell diameter to be 2 times bundle dia.
shell dia. mm 992
Liquid level from base mm 800
freeboard mm 192
Height of Catalyst Bed
Weight of Catalyst Kg 25.32357959
Density of Catalyst lb/ft^3 100
Kg/m^3 1601.85
Volume of Catalyst m^3 0.015808958
Dia of Catalyst Bed mm 992 inch 39.05512
Height of Catalyst Bed m 0.204519026
Lemgth of Tube m 4.88
Total m 5.084519026
taking a favtor of 1.5 to accommodate space on top and bottom
Total Height m 7.626778539

Formaldehyde 2014
ABSORPTION COLUMN
 ABSORBER DESIGN
One of the most common unit operations in the industry is the absorption process.
Absorption is the mechanism of transporting molecules or components of gases into
liquid phase. The component that is absorbed is called the solute and the liquid
that absorbs the solute is called the solvent. Actually, the absorption can be either
physical where the gas is removed due to its high solubility in the solvent, or
chemical where the removed gas reacts with the solvent and remains in solution.
 PACKED-BED ABSORBER
The packed-bed absorbers are the most common absorbers used for gas removal.
The absorbing liquid is dispersed over the packing material, which provides a large
surface area for gas-liquid contact. Packed beds are classified according to the
relative direction of gas-to-liquid flow into two types. The first one is co-current
while the second one the counter current packed bed absorber. The most common
packed-bed absorber is the counter-current flow tower. The gas stream enters the
bottom of the tower and flows upward through the packing material and exits from
the top after passing through a mist eliminator.
Liquid is introduced at the top of the packed bed by sprays or weirs and flows
downward over the packing. In this manner, the most dilute gas contacts the least
saturated absorbing liquid and the concentration difference between the liquid
and gas phases, which is necessary or mass transfer, is reasonably constant through
the column length. The maximum (L/G) in counter-current flow is limited by
flooding, which occurs when the upward force exerted by the gas is sufficient to
prevent the liquid from flowing downward. The minimum (L/G) is fixed to ensure
that a thin liquid film covered all the packing materials.
 PACKING MATERIAL
The main purpose of the packing material is to give a large surface area for mass
transfer. However, the specific packing selected depends on the corrosiveness of
the contaminants and scrubbing liquid, the size of the absorber, the static pressure
drop, and the cost. There are three common types of packing material: Mesh,
Ring, and Saddles. In our project Ceramic Berl Saddles packed was selected since it
is good liquid distribution ratio, good corrosion resistance, most common with
aqueous corrosive fluids and Saddles are beast for redistributing liquids low cost.
Also we use 2 inches diameter packing.

Formaldehyde 2014
 SIZING OF PACKED TOWER
ASSUMPTIONS
Some assumptions and conditions were design calculation based on:
1. G and L are representing the gas and liquid flow rates.
2. x and y are for the mole fraction of Methanol in liquid and gas respectively.
3. Assuming the column is packed with (2” Ceramic Berl_ Saddle).
PACKED TOWER DIAMETER:
Gas velocity is the main parameter affecting the size of a packed column. For
estimating flooding velocity and a minimum column diameter is to use a
generalized flooding and pressure drop correlation. One version of the flooding and
pressure drop relationship for a packed tower in the Sherwood correlation, shown
in Figure 2.
Packing diameter calculation:
The gas flow rate G= 6670.781 kg/h
The liquid flow rate L= 1549.818
Calculate the value of the abscissa ε
Where: L and G = mass flow rates (kg/h)
ρ_g = density of the gas stream
ρ_l = density of the absorbing liquid
ρ_g = 1.605 kg/m^3
ρ_l = 995 kg/m^3
Fp = 150m^(-1)
µ = 0.000797 P
gc = 9.8 m/s^2
Flow factor = 0.013706

Formaldehyde 2014
From the figure
using flooding line, ε = 0.2
Where
G' = mass flow rate of gas per unit cross-sectional area of column, g/s•m2
ρ_g = density of the gas stream
ρ_l = density of the absorbing liquid
gc = gravitational constant,
F = packing factor given
ᵠ = ratio of specific gravity of the scrubbing liquid to that of water
µ = viscosity of liquid
G‟flooding = 9.323643
G‟ operating = 0.55 (G‟ flooding) = 5.128
area of packing = 0.361348 (G/G‟operating)
D_packing = 0.6784m
Packing diameter, D_tower =0.8480 (D_packing*1.25)
column diameter = 1.0m (roundoff)

Formaldehyde 2014
PACKING HEIGHT

Formaldehyde 2014
CALCULATING NOG AND Z
Z= HOG *NOG
NOG = number of transfer units based on an overall gas-film coefficient.
HOG = height of a transfer unit based on an overall gas-film coefficient, m
yA,in = mole fraction of solute in entering gas
YA,out = mole fraction of solute in exiting gas
yA,in = 0.27778
yA,out = 0.007
Y*
A,in = 0.20
Y*
A,out = 0.0001
NOG = 9.2540
HOG obtained from table 15-4 in “Separation Process Engineering”.
For ceramic packing with size 2 inch,
HOG = 3 ft = 0.9 m
Z= HOG *NOG = 8.32 m
Z_column = Z_packing*(1+0.25)
Z_column = 10.41m

Formaldehyde 2014
DISTILLATION COLUMN
The problem of determining the stages and reflux requirements for
multicomponent distillations is much mo4re complex than for binary mixtures.
With a multicomponent mixture, fixing one component composition does not
uniquely determines the other component compositions and stage temperature.
Also when feed contains more than two components, it is not possible to specify
the complete composition of the top and the bottom products independently. The
separation between top and the bottom products is specified by setting limits on
two “key” components, between which it is deserved to make the separation.
KEY COMPONENTS
The light key will be the component that it is desired to keep out of the bottom
product, and the heavy key the component to be kept out of the top product.
Here the light component is Methanol while the heavy component being Water.
MULTICOMPONENT DISTILLATION FOR STAGE AND REFLUX
REQUIREMENT
Hengstebeck‟s Method:
For any component i the Lewis-Sorel material balance equation and equilibrium
relation can be written in terms of individual component molar flow rates; in the
place of component composition:
vn+1,i = ln+1 + di
vn, i = Kn, i (V/L) ln,i
For the stripping section :
l’n+1, i = v’n, 1 + bi
v’n, 1 = Kn, i (V’/L’) l’n,i

Formaldehyde 2014
where :
ln+1 = the liq. flow rate of any component i from the stage n,
vn, i = the vapour flow rate of any component i from the stage n,
di = the flow rate of the component i in the tops,
bi = the flow rate of the component i in the bottoms,
Kn, i = the equilibrium constant for component i at the stage n.
The subscript „ denotes the stripping section.
V and L being the total flow rates, assumed constant.
To reduce a multicomponent system to an equivalent binary system it is necessary
to estimate the flow rate of the key component throughout the column. This
method assumes that in a typical distillation the flow rates of each of the light
non-key components approaches a constant, limiting , rate in the rectifying
section; and the flow of each of the heavy non-key components approach limiting
flow rates in the stripping section.
Thus we have for the rectifying section :
Le = L - ∑li
Ve = V - ∑vi
And for the stripping section:
L’e = L’ - ∑l’i
V’e = V’ - ∑v’i
Where
Ve and Le are the estimated flow rates of the combined keys.
li and vi are the limiting liquid and vapour rates of the components lighter than the
keys in the rectifying section.
L‟i and v‟i are the limiting liquid and vapour rates of the components heavier than
the keys in the stripping section.

Formaldehyde 2014
Then we have:
li = di/(αi-1)
vi=li + di
v’i = αibi/(αLK-αi)
l’i = v’i + bi
where αi = relative volatility of the component i, relative to to the heavy key HK
and αLK = realtive volatility of the light key (LK), relative to the heavy key.
The equilibrium live was drawn using the relation
y= αLKx / ( 1 + (αLK-1)x )
where x and y refers to the liquid and vapour concentrations of the light key.
FINDING THE MINIMUM NUMBER OF STAGES
The Fenske equation have been used to estimate the minimum number of stages at
the total reflux condition. The equation is:
[ xi / xr ] = αi
Nm
[ xi / xr ]b
[ xi / xr ] = the ratio of the concentration of any component i to the concentration
of a reference component r and the suffixes b and d denote the distillate and the
bottoms respectively.
Nm = minimum number of stages at the total reflux condition.
αi = average relative volatility of the component i with respect to the reference
component.

Formaldehyde 2014
If the number of stages is known then the above equation can be used to estimate
the split of components between the top and the bottom at total reflux. Thus we
have:
di/ bi = αi
Nm
[ dr / br ]
Where di and bi are the flow rates of the component i in the tops and the
bottoms.
And dr and br are the flow rates of the reference component in the tops and the
bottoms.
We also have di + bi = fi wher fi is the flow rate of the component i.
MINIMUM REFLUX RATIO
The equation is:
∑ [αi xi,d / (αi - ɵ ] = Rm + 1
Where:
αi = relative volatility of component i with respect to some reference component,
usually the heavy key.
Rm = the minimum reflux ratio.
xi,d = concentration of component i in the tops and bottoms.
ɵ root of the equation : ∑ [αi xi,f / (αi - ɵ ] = 1-q
where xi,f = the concentration of the component i in the feed and q depends upon
the condition of the feed.
FEED POINT LOCATION
The empirical relation used is :
log [ Nr / Ns] = 0.206log[ ( B/D)( xf,HK/ xf,LK ) (xb,LK/ xb,HK)2
]
Nr = number of stages above the feed, including any partial condenser.

Formaldehyde 2014
Ns = number of stages below the feed, including the reboiler.
B = molar flow of bottom product.
D = molar flow of top product.
xf, HK = concentrations of the heavy key in the feed
xf, LK = concentrations of the light key in the feed.
xb, LK = concentrations of the heavy key in the top product.
xb, HK = concentrations of the light key if in the bottom product.
EFFICIENCY
The overall column efficiency is obtained by O‟ Connell correlation:
Eo = 51 – 32.5 log (µaαa)
Where µa = molar average liquid velocity.
αa = average molar volatility of the light key.
MATERIAL COMING FROM ABSORBER
MOLES/S MOL. WT. G/SEC
FLOW RATE OF METHANOL 8.70165 32.06 278.9749
FLOW RATE OF
WATER 41.4659 18 746.3862
FLOW RATE OF FORMALDEHYDE (IN WATER) 14.265 30.02 428.2353
TOTAL SOLUTION 64.43255 1453.5964
PERCENTAGE OF FORMALDEHYDE IN WATER 0.2213943 0.294604
PERCENTAGE OF METHANOL IN SOLUTION 0.1350505 0.1919205
OPERATING CONDITIONS AND VARIABLES
UNIT
PRESSURE OF THE COLUMN atm. 1
DEW
POINT deg C
66.5 deg
C
BUBBLE POINT deg C
97.6 deg
C
K's VALUES AT 1 atm AND DIFFERENT TEMP.

Formaldehyde 2014
Feed Specifications
COMPONENT FEED TOP BOTTOM
METHANOL 8.70165 8.151891 0.549759
WATER 40.3559 0.360068 40.78652
FORMALDEHYDE 14.265 0.014265 14.25074
TOTAL 63.32255 8.526224 55.58702
COMPONENT Xd Xb Xf
METHANOL 0.956096 0.00989 0.137418
WATER 0.042231 0.733742 0.637307
FORMALDEHYDE 0.001673 0.256368 0.225275
LIGHT KEY METHANOL
HEAVY KEY WATER

Formaldehyde 2014
BUBBLE POINT CALCULATION
TEMP.
150 deg
C 99.9 97.6
COMPONENTS Xb Ki Ki*Xi Ki Ki*Xi Ki Ki*Xi
METHANOL 0.00989 3.004 0.02971 2.595 0.025665 2.589 0.025605
WATER 0.733742 2.46 1.805005 1.198 0.879023 1.105 0.810785
FORMALDEHYDE 0.256368 1.22 0.312769 0.73 0.187149 0.693 0.177663
TOTAL 2.147484 1.091836 1.014053
BUBBLE POINT 97.6 deg C
DEW POINT CALCULATIONS
67.1 deg C 72.1 66.5 deg C
COMPONENTS Xd Ki Xd/Ki Ki Xd/Ki Ki Xd/Ki
METHANOL 0.956096 1.094 0.873945 1.435 0.666269 1.05 0.910568
WATER 0.042231 0.491 0.086009 0.394 0.107184 0.52 0.081213
FORMALDEHYDE 0.001673 0.266 0.00629 0.336 0.004979 0.26 0.006435
TOTAL 0.966245 0.778433 0.998216
DEW POINT TEMP. 66.5 deg C
EQUILIBRIUM DATA
RELATIVE VOLATILITY=Ki/K FOR HEABY KEY
TOP BOTTOM AVERAGE
TEMP. 66.5 97.6
COMPONENTS Ki Ai Ki Ai Ai
METHANOL 1.05 2.019231 2.589 2.342986 2.181109
WATER 0.52 1 1.105 1 1
FORMALDEHYDE 0.26 0.5 0.693 0.627149 0.563575
EQUIL. DATA: y=Ai(LK)*x/(1+ (Ai(LK) - 1)*x) OPERATING LINES
TOP BOTTOM
X Y X Y X Y
0 0 0.958 0.957699 0 0.0133
0.1 0.195071 0.209 0.32168 0.2 0.328138
0.2 0.352867
0.3 0.48314 NO. OF STAGES DATA

Formaldehyde 2014
0.4 0.592514 X Y X Y
0.5 0.685644 0.013 0.0133 0.249776 0.4
0.6 0.765899 0.013 0.02856 0.249776 0.4
0.7 0.835776 0.023 0.02856 0.325915 0.4
0.8 0.897166 0.023 0.048442 0.325915 0.5
0.9 0.951527 0.035 0.048442 0.434847 0.5
1 1 0.035 0.073698 0.434847 0.6
0.051 0.073698 0.568191 0.6
Line: Y=X 0.051 0.104778 0.568191 0.7
X Y 0.07 0.104778 0.703466 0.7
0 0 0.07 0.141559 0.703466 0.8
1 1 0.093 0.141559 0.81692 0.8
0.093 0.18313 0.81692 0.9
0.119 0.18313 0.897845 0.9
0.119 0.22774 0.897845 1
Sample Point calculations 0.147 0.22774 0.949137 1
EQUIL. POINT 0.147 0.273025 0.949137 1
X Y 0.175 0.273025
0.949137 0.97602 0.175 0.316474
0.202 0.316474
BOTTOM OPERATING LINE POINT 0.202 0.355965
X Y 0.25 0.355965
0.202175 0.316474
TOP OPERATING LINE POINT
X Y
0.949137 0.950421
TOP BOTTOM
MOLE/S Ai Li Vi MOLE/S Ai Vi Li
8.151891 2.181109 6.901898 15.05379 14.25074 0.6 4.965182 19.2159
TOTAL 6.901898 15.05379 4.965182 19.2159
(CHOOSING REFLUX RATIO OF 1.5 TIMES MIN. REFLUX RATIO)
EQUIL. L 57.84328 EQUIL. L 110
EQUIL
V. 58.21762 EQUIL. V 68
SLOPE OF OPERATING LINE (TOP) SLOPE OF OPERATING LINE (BOTT
EQUIL L/EQUIL V 0.85
EQUIL
L/EQUIL V 1.605161
xb 0.0133
xd 0.957699
xf 0.177376

Formaldehyde 2014
MIN. REFLUX RATIO
MIN. NUMBER OF STAGES NUM.
3.22521
7
DEN.
0.33867
7
NO.
9.52297
8
MIN. REFLUX RATIO
TRY
Xf Ai Ai*Xf Theta 1.4 1.5 1.6 1.7
1.
8 1.9
0.13741
8
2.18110
9
0.29972
4
0.38371
6 0.44
0.51577
9
0.62298
5
0.
8 1.06622
0.63730
7 1
0.63730
7 -1.59327
-
1.27
5 -1.06218 -0.91044
-
0.
8 -0.70812
0.22527
5
0.56357
5
0.12695
9 -0.15179
-
0.13
6 -0.1225 -0.11172
-
0.
1 -0.095
-1.36134 -0.97 -0.6689 -0.39917
-
0.
1
0.26310
2
Xf Ai Ai*Xf Theta 2 1.85 1.83 1.84
0.13741
8
2.18110
9
0.29972
4
1.65493
8
0.90
5
0.85364
9
0.87867
5
0.63730
7 1
0.63730
7 -0.63731 -0.75 -0.76784 -0.7587
0.22527
5
0.56357
5
0.12695
9 -0.08839
-
0.09
9 -0.10025 -0.09946
0.92924
6
0.05
7 -0.01444
0.02051
1
THETA VALUE 1.84
Xd Ai Xd*Ai
THET
A 1.84
0.95609
6
2.18110
9 2.08535
6.11344
9
0.04223
1 1
0.04223
1 -0.05027
0.00167
3
0.56357
5
0.00094
3 -0.00074
TOTAL
6.06243
5

Formaldehyde 2014
MIN. REFLUX RATIO
5.06243
5
Calculations For Entering the feed
Xb(LK) 0.00989
Xd(HK)
0.04223
1
Xf(LK)
0.13741
8
Xf(HK)
0.63730
7
Method Employed is Kirkbride equation
Total Bottom
product
55.5870
2
Total Distillate product
8.52622
4
log (Nr/Ns)
0.04524
8
Nr/Ns 1.1098
Total Number of stages 18
Total Number of stages excluding Reboiler and Condenser 17
Ns
8.05763
6
so the feed should enter at the plate 8
From the graph it comes out to be 9
Approximately equal

Formaldehyde 2014
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1
molefractionofFormaldehydeinMethanol
mole fraction of Formaldehyde in Water
FIGURE 9: Equilibrium data and number of Stages

Formaldehyde 2014
Dia And Height Calculation
Number Of Stages: 18
Slope of Top Operating Line 0.85
Slope of Bottom Operating Line 1.605161
Top Composition (Essentially Methanol) 96
Bottom Composition (Essentially Formalin) % Formaldehyde 26
Reflux Ratio 7.593
Flow Rate in gm/sec 1453.596
Flow Rate in moles/sec 64.43255
Flow Rate in Kg/hr 5232.947
Top Product 965.7327
Vapor Rate at Top 8298.541
Bottom Product 4267.214
Material Balance Gives:
Vm at bottom 7051.367
Liq. Flow Rate at Bottom 4392.934
Column Efficiency in % 60
Real Stages 28.33333 or 29
Assuming 100 mm water Pressure Drop per Plate (All in Pa)
Column pressure Drop 28449
Top Pressure Drop 101325
Bottom pressure 129774
Base Densities:
Liquid Density 1111
Vapor Density 0.695
Surface Tension 0.018
Top Densities:
Liquid Density 792
Vapor Density 1.13073
Surface Tension 0.0469
Tray Spacing taken to be 0.5 m
Column Diameter: K1
F(LV) at Bottom 0.040147 0.08
F(LV) at Top 0.032117 0.08
Correction For Surface Tension
At Bottom 0.078332

Formaldehyde 2014
At Top 0.094868
Base Velocity: in m/sec 3.130886
Top Velocity: in m/sec 2.508947
Designing Done for 85 % flooding
Base Velocity: in m/sec
2.66125
3
Top Velocity: in m/sec
2.13260
5
Maximum Flow Rate
Base m^ 3/sec
2.81829
2
Top m^ 3/sec
2.03863
9
Net Area Reqd.
Base m^ 2
1.05900
9
Top m^ 2
0.95593
9
Downcomer Area Taken as 12 % of total Area
Base m^ 2 1.20342
Top m^ 2
1.08629
4
Column Diameter:
Base m
1.23775
7
Top m
1.17598
2
Height Claculation:
Totla Number of Trays 29
Crude Hright for Column m 14.5
(number of stages * tray spacing)
Choosing 30 % more space for free space at top and bottom
Additional Hright m 4.35
Total height m 18.85
Or after rounding off, Total height m 19

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Number of stages after taking efficiency into consideration
Top Temperature in º C 66.5
Bottom Temperature in º C 97.6
Average Temperature in º C 82.05
Vicosities:
Methanol 0.29
Water 0.35
Formaldehyde 1.87
Molar Average Viscosity in Feed 0.684
Average viscosity for Light Key
2.18110
9
so Efficiency from graph almost 100%
so Number of stages is still 18
Number of Stages (Real, 60% column efficiency) 29

Formaldehyde 2014
CONDENSER
Shell and tube exchangers can be effectively used as condensers which are
employed more preferably than direct contact condensers. There are 4 types of
condenser configurations available. They are :
1. Horizontal, with condensation in shell and cooling medium in tubes.
2. Horizontal, with condensation in tubes and cooling medium in shell.
3. Vertical, with condensation in shell and cooling medium in tubes.
4. Vertical, with condensation in tubes and cooling medium in shell.
Of which horizontal shell side and vertical tube side are the most commonly used
ones. A horizontal exchanger with condensation in tubes is rarely used as a process
condensers but is the usual arrangement for heaters and vaporizers using
condensing steam as the heating medium.
In the formaldehyde process, the condenser used is total condenser. The outlet
stream is condensed methanol which is recycled back to the fresh feed. Thus the
overall economy of the process increases. The reflux ratio of 1.5 times the
minimum is utilized in the distillation column which gives the amount of methanol
recycled and produced.
Condenser Mainly has Methanol Condensing in it With Small Amount of
Water Present in it
COMPONENT TOP Xd
METHANOL 8.151891 0.956096
WATER 0.360068 0.042231
FORMALDEHYDE 0.014265 0.001673
Feed
TOTAL 63.32255 8.526224
Average Molecular Weight of Vapors 31.5
(For Simplicity Taken As 96 % Methanol And 4% Water)
Condensing Temp. of Methanol 64 deg. C
(Taken fom J. H. Perry)

Formaldehyde 2014
Actual Condensing Temp. of Methanol deg. C 50
(Design Temp. of Condnsation)
Inlet Temp. of Methanol Vapors deg. C 66.5
Cooling Medium Cold Water
Water Inlet Temp. deg. C 25
Water Inlet Temp. (max.) deg. C 35
Enthalpy of Sat. Vap. KJ/Kg 1492.1
Enthalpy of Sat.
Liq. KJ/Kg 391.7
Flow Rate of Methanol 965.7326988
Heat transferred from Vapor KW 295.1922949
(Flow rate of methanol * (Enthalpy of Sat. Vap.- Enthalpy of Sat. Liquid)
Cooling Water Flow Kg/sec 7.062016626
(Heat reqd. for condensatio/(temp. diff.* sp. Heat))
Assumed Overall Coefficient W/m^2 deg. C 500
LMTD Calculations:
Temp. correction factor R 1.65
S 0.240964
LMTD Temp. deg. C 28.12493
Correction Factor Ft 0.96
Corrected LMTD Ft*LMTD 26.99993
Choosing 20 mm O.D. 16.8 mm I.D. 4.88 m (16 ft) long brass tubes
Tube ID mm 16.8
Tube OD mm 20
Tube Length m 4.88
Trial Area m^2 21.86615
( Heat Required/(Assumed U* LMTD))

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Number of Tubes 71.30441 or
(Area of heat trensfer reqd./ area of one tube) 72
Employing One Shell Two Tube Pass
Triangular Pitch since fouling is very less mm 25
Tube Bundle Dia., Db mm 260.7226
Number of Tubes in Center 10.4289
Shell side Heat Tranfer Coeff. Calculation
Assumed Shell-side Coefficient W/m^2 deg. C 3500
From the Chart given in Coulson Richardson, Vol. 6
Mean Temp.
Shell-side deg. C 58.25
Tube-side deg. C 30
(H51-Tw) deg. C 4.035714
Tw 54.21429
Mean Condensate Temp. deg. C 56.23214
Viscosity
mN
s/m^2 0.38
Liq. Density Kg/m^3 792
Vap. Density Kg/m^3 1.13073
K (thermal conductivity) W/m deg. C 0.192
Load Kg/sm 0.000763
where
Nt total number of tubes in the bundle
L tube length
wc
total condensate
flow
Nr = 2*Number of tubes in center/3 6.952603
average number of tubes in the bundle

Formaldehyde 2014
Heat Transfer Coeff. W/m^2 deg. C 3652.902
So, Heat Transfer Coeff. Came quite close
Tube side Heat Transfer coeff.
Tube-Side Coefficient. W/m^2 deg. C
Tube Cross Sectional Area m^2 0.003991
Density of Water Kg/m^3 994
Tube Velocity m/sec 1.780349
Tube-Side heat trasf.Coeft.. W/m^2 deg. C 7389.688
Over-All Heat Transfer Coeff. W/m^2 deg. C
Fouling Factors for Both side W/m^2 deg. C 2000
Conductive Heat Transf. Coeff.of Tubes 50
1/U 0.001565
1/U= outer dia*inner dia./tube side coeff. + 1/shell side coeff. +1/foulingcoeff.
...+ outer dia./(fouling*inner dia) + outer dia.*LN(outer dia./innerdia)/(2*tube thermal conductivity)
U
(inverse of
1/U) 638.9926
Since, U comes out close to assumed heat transfer coeff. Of 500
And the deviation is on positive side. We can take the arrangement
of shell and tube condenser as above to be satisfactory

Formaldehyde 2014
REBOILERS
Reboilers are used with distillation columns to vaporize a fraction of bottom
product whereas in a vaporizer essentially all feed is vaporized thus in this way
they differ from a vaporized.
TYPES OF REBOILERS
 Forced circulation: pump is required for this kind of reboiler. It is used
essentially for reboiling viscous and fouling fluids.
 Thermosyphon natural circulation reboiler: it can be horizontal or vertical.
Liquid circulation is maintained by the difference and density between two-
phase mixture of vapour and liquid. A disengagement vessel will be required
for this reboiler.
 Cattle type reboiler: Boiling takes place on tubes immersed in a pool of
liquid. There no circulation of liquid through exchanger and they are not
suitable for fouling materials and have a high residence time.
SELECTION OF REBOILER
In our case, Thermosyphon reboiler is used. In this type, the heat available in
bottom feed is utilized. This type of reboiler requires a minimum head so that it
can take advantage of density difference thus the support of distillation column
and reboiler needs to be elevated and the cost increases. But the higher cost is
offset by the economic usage of available heat which otherwise would have been
lost.

Formaldehyde 2014
BOILER DESIGN
COMPONENT FEED TOP BOTTOM
METHANOL 8.70165 8.151891 0.549759
WATER 40.3559 0.360068 40.78652
FORMALDEHYDE 14.265 0.014265 14.25074
TOTAL 63.32255 8.526224 55.58702
COMPONENT Xd Xb Xf
METHANOL 0.956096 0.00989 0.137418
WATER 0.042231 0.733742 0.637307
FORMALDEHYDE 0.001673 0.256368 0.225275
LIGHT KEY METHANOL
HEAVY KEY WATER
Vaporisation Rate Reqd. Kg/hr 7051.367
Boiling Point of Formalin solution deg. C 99.7
Steam available at Pressure atm. 2.85
Temp. deg. C 132.22
(Ref: McCabe Smith, Appendix 8)
Latent Heat of Vaporisation KJ/Kmol 30176
(Ref: McCabe Smith, Appendix 3)
Critical
Temperature deg. C 586.0482
(Ref: J. H. Perry)
Mean Overall diff.
T deg. C 32.52
Reduced Temp. deg. C 0.635955
(Boiling Point in K/Critical Temp.)
Molecular Weight 21.152
From Fig. Heat Flux W/m^2 deg C 42000
Heat Load KW 592.8398

Formaldehyde 2014
(Flow Rate*Latent Heat of Vaporisation/(3600*Boiling Point)
Area Required m^2 14.11523
(Heat Load/ Heat Flux)
Choosing 20 mm O.D. 16.8 mm I.D. 4.88 m (16 ft) long brass tubes
Tube ID mm 16.8
Tube OD mm 20
Tube Length m 4.88
Area of one tube m^2 0.303
Number of Tubes reqd. 46.58493
Calculation for Bundle Dia. 207.77
A dixed tube sheet can be used for a thermosyphon reboiler
(from fig. 12.10, diametrical clearence)
Diametrical Clearence mm 14
Shell Inside dia. mm 221.77
( Bundle dia. + diametrical clearence )

Formaldehyde 2014
PHYSICAL DESIGNING OF SOME OTHER EQUIPMENTS
The plant has beside the major equipments like reactor, distillation column and
absorber column several other heat tansfer and mass transfer equipments. For
example; heat exchangers are used extensively in the chemical plants. These heat
exchangers are required for utilising the heat in the effluent gases. Furnaces are
there to provide extra heat needed and which is not available in the process
streams. Likewise, pumps, compressors and blowers are used to transfer solid,
liquid and gases. A sample designing of some them used in the formaldehyde plant
is given here.
PUMPS
Total moles of methanol( feed + recycle) for 1 mol of formaldehyde = 1.74
HCHO production rate = 14.265 mols / sec
Hence methanol reqd. = 1.74 * 14.265 = 24.8215 mol / sec
Viscosity of methanol at 35o
C = .48 Cp
(reference J.H.Perry , nomograph for viscosity of liquids )
weight of methanol = 24. 8215 * 32.06 = 7.96 Kg / sec
Density of methanol = 1015 Kg/m3
Flow rate of methanol = 0.808 * 10-3
m3
/sec
SELECTION OF PUMP
Using graph between flow rate on x axis and pressure required on y axis from
Donald R Woods suitable pump is Centrifugal Pump.

Formaldehyde 2014
Head to be developed = 35- 14.7 = 20.3 Psia. = 1.05 m of water.
Single stage Centrifugal pump is sufficient.
Power required ( reference : fig 2-29 , page 2-27 , D R Woods)
Liquid flow rate = 0.808 L/Sec
Head = 1.05 m of water.
Now assuming 60% efficiency of the pump ,
The pump gives 0.1 KW for water so for methanol=0.1 * 1.015=0.1015 KW
Pipe size selection
Choosing from pump-heat exchanger combination pipe size available from [ fig 2-
30 , Page 2-28 ,D.R. Woods]
Pipe size available = 2.5 cm.
Velocity of methanol = v * 3.142 * d2
/4 = 0.808 L/sec
Hence v = 1.64 m/sec
Pressure loss
∆P / g = 4f( L/ D)* (<v>2
/ 2g)
thus ∆P/ 100m = 4 * 0.009 * 1015 * 100 * 1.642
/ ( 2.5 * 10-2
) = 393 KPa / 100 m
Reynolds no. = d v ρ / µ=2.5 * 10-2
* 1.64 * 1015 / (0.48 * 10-3
) = 86697.92
Material K K /D f

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Cast Iron 0.00085 0.0016 0.009
Wrought Iron 0.00015 0.000292 0.0038
(reference : Mc Cabe Smith , Page 101 , ed 4th
)
NPSH required = (pressures supplied at flange)- ( vapour pressure of liquid at
pumping temperature + friction losses )
Vapour pressure of methanol at 35 o
C ( 308 K)
Ln P = 7.209 – (1582.30 / ( T – 33.45))
Ln P = 7.209 – (1582.30 / ( 308 – 33.45))
= 1.445
thus P = 27.91 KPa
NPSH required = 101.325 – 27.91 KPa = 83.525 KPa = 0.64 m water head
BLOWER
Air required per mol of HCHO = 4.019 moles.
100 tonnes/ day of HCHO means
(100 * 103
* 103
* 0.37 ) / ( 30.02 * 24 * 3600) = 14.265 moles/ sec
So air required = 57.332 moles
Taking air to be an ideal gas amd air entering at the room temp. and at a pressure
of 14.7 psia.
Volume of air required per sec
= 57.332 * 22.4 * 10-3
= 1.284 m3
/ sec = 1284 dm3
/ sec
Pressure at which air is reached = 35 psia.
∆P= 35 – 14.7 psia = 20.3 psia.=139.925 KPa.

Formaldehyde 2014
Here multi stage blower have to be used.
Efficiency is taken to be 80% for compressors and 60% for fans.
Compressors used here are of 250 KW
At inlet pressure ( 14.7 psia or 100 KPa) so pipe would be 10 cm in dia. [ fig 2-13]
Velocity = 20m/sec
At outlet pressure ( 35 psia) so the fig [ fig 2-13] cannot be used.
ρ1= MP1/RT
ρ2= MP2/RT
Thus we have d2= d1 ( P1 / P2)1/2
hence d2 = 10 (35 / 14.7) cm = 15.43 cm.
PRESSURE DROP
∆P / g = 4f( L/ D)* (<v>2
/ 2g)
thus ∆P/ L = 4* 0.0032 * 20 * 20 * 1.1614 /( 2 * 50 * 10-2
)
= 7.06 KPa / 100 m.
Reynolds no. = d1 v ρ1 / µ
d1 = 10 * 10-2
m
v = 20 m /sec.
µ= 0.185 * 10-4
pa
(reference : J.H. Perry , Table 2.229)
Re = 10 * 10-2
* 20 * 1.1614 / ( 0.185 * 10-4
) = 1.256 * 105
(reference : Mc Cabe Smith , Page 101 , ed 4th
)
Material K K /D f

Formaldehyde 2014
Cast Iron 0.00085 0.0016 0.0062
Wrought Iron 0.00015 0.000292 0.0038
VALVE DESIGN
Valves are used to control pressure condition of flowing streams. Valves and vents
are needed as the as like in the reactor, the reactions might be occuring at the
high pressure. But the downstream gases, in this case going to absorber needs to
be brought down in the pressure.
Incoming Pressure = 25 psia.
Outgoing Pressure = 16.17 psia
Pressure equation is:
∆P = k * 0.6 * ρ * v2
/(1.22 *10)
where k = length factor for the valves
ρ = density of fluid
v = velocity of fluid
ρ = density of gases = M * P/(R * T)
where M = Avg. Mol. Wt.
P = pressure of gases
R = Universal Gas Constant
T = Temp.
ρ = 25.68 * 25 / 14.7
0.0821 * 616
ρ = 0.864 Kg/m3
∆P = (25 – 16.17)/14.7 *76

Formaldehyde 2014
this gives k = ∆P * 1.22 *10/( 0.6 * ρ * v2
)
k = 6.08
so, we can use globe valve
equivalent L/D = 320
Similarly, other valves can be designed as given.
AIR FILTER
Air-Filter Types Air filters may be broadly divided into two classes:
(1) Panel, or unit, filters;
(2) Automatic, or continuous, filters.
Panel filters are constructed in units of convenient size (commonly 20- by 20-in or
24- by 24-in face area) to facilitate installation, maintenance, and cleaning. Each
unit consists of a cleanable or replaceable cell or filter pad in a substantial frame
that may be bolted to the frames of similar units to form an airtight partition
between the source of the dusty air and the destination of the cleaned air. Panel
filters may use either viscous or dry filter media. Viscous filters are so called
because the filter medium is coated with a tacky liquid of high viscosity (e.g.,
mineral oil and adhesives) to retain the dust. The filter pad consists of an assembly
of coarse fibers (now usually metal, glass, or plastic). Because the fibers are
coarse and the media are highly porous, resistance to air flow is low and high
filtration velocities can be used. Dry filters are usually deeper than viscous filters.
The dry filter media use finer fibers and have much smaller pores than the viscous
media and need not rely on an oil coating to retain collected dust.
Automatic filters are made with either viscous-coated or dry filter media.
However, the cleaning or disposal of the loaded medium is essentially continuous

Formaldehyde 2014
and automatic. In most such devices the air passes horizontally through a movable
filter curtain.
HEPA (HIGH-EFFICIENCY PARTICULATE AIR) FILTERS
These were originally developed for nuclear and military applications but are now
widely used and are manufactured by numerous companies. By definition, an HEPA
filter is a “throwaway, extended-medium dry-type” filter having (1) a minimum
particle-removal efficiency of not less than 99.97 percent for 0.3-mm particles, (2)
a maximum resistance, when clean, of 1.0 in water when operated at rated air-
flow capacity, and (3) a rigid casing extending the full depth of the medium
(Burchsted et al., op. cit.). The filter medium is a paper made of submicrometer
glass fibers in a matrix of larger-diameter (1- to 4-mm) glass fibers. An organic
binder is added during the papermaking process to hold the fibers and give the
paper added tensile strength. Filter units are made in several
standard sizes. Air filters used in nuclear facilities as prefilters and buildingsupply
air filters are classified as shown in Table 17-10.
TABLE 9.
Other table presents the relative performance of Group I, II, and III filters with
respect to airflow capacity, resistance, and dust holding capacity. The dust-
holding capacities correspond to the manufacturers‟ recommended maximum

Formaldehyde 2014
allowable increases in airflow resistance. The values for dust-holding capacity are
based on tests with a synthetic dust and hence are relative. The actual dust-
holding capacity in a specific application will depend on the characteristics of the
dust encountered. In some instances it may be appropriate to use two or more
stages of precleaning in air-filter systems to achieve a desired combination of
operating life and efficiency. In very dusty locations, inertial devices such as
multiple small cyclones may be used as first-stage separators.
Table 10 : Air Flow Capacities and Resistance Holding Capacity for different
Filters
Table 11 : Removal Efficiency of different Filters

Formaldehyde 2014
MECHANICAL DESIGN
REACTOR MECHANICAL DESIGN
Reactor Data
Diameter = 1.2 m
Height = 6 m
Top and Bottom: Toro spherical head
Operating Pressure of Reactor: 1.1 atm.
Operating Temperature of Reactor: 873 K
Thickness of Shell, t= p*d/(2*f*E) + c
Where c= corrosion allowance
E= 13.37 Kg/m2
t = 16.8*1.01325*10 5/(2*13.37*10 6* 0.85)=7.4 mm
c= 3 mm
hence t= 10mm
Torospherical head figure 11: Torospherical Head
(Ri- ri)2
– (Ri-hi)2
= (R-ri) b
or Ri-hi = ((Ri - R)- (Ri + R-2ri))1/2 S
f Ri
Considering : Ri / D = 0.8 R
Or Ri = 0.8 * 1200 mm = 960 mm
Also ri / D = 0.1
Or ri = 0.1 * 1200 mm = 120mm
hi = 960 – ((960 – 496 )( 960+496-2*120))1/2
= 223.74 mm
zi = hi / 3 = 223.24 / 3 = 74.58mm
now, the volume of the head is given by
vh = (∏D2
L / 4 + 0.7D3
/2)

Formaldehyde 2014
where D is 1200 mm
l= 74.58 mm
hence vh = 0.4 m3
Thickness of head
t=p * w /(2fE-0.2* p) + c
where t = thickness of head.
P = pressure inside vessel.
W = stress intensification factor for torospherical dished head.
c= corrosion allowance
w = ¼ * ( 3 + ( rc / ri)1/2
)
w = ¼ * ( 3 + ( 960 /120)1/2
) = 1.46
p= 1.68 kg/mm2
hence t = 1.68 * 960 * 1.46 / (2 * 13.37 * 0.85 –0.2 * 1.68) = 2.14 mm
but the minimum thickness has to be taken = 3 mm
corossion allowance = 3 mm
hence total thickness = 6 mm
Design of flat head
p= 1.1 * 101.325 / 1000. = 0.1114 kg/mm2
t = D * (∆p / fall)0.5
=0.05 mm
but the minimum thickness has to be taken = 3 mm
corrosion allowance = 3 mm
Hence total thickness = 6 mm
2 openings are to be provided for water inlet and steam outlet.
And 2 openings are to be provided for inlet gases and outlet reactor effluent stream.
Velocity of gases maintained :
Velocity in tube = tube length / residence time = 6 / 0.02 = 300 m/ sec.

Formaldehyde 2014
Area of tubes * vt = area of shell * vs
vs = vt * (Dt / Ds )2
vs = 224 * ( 16 / 992)2
= 0.56 m/sec
But due to some velocity head loss and since the velocity of gases before entering the
reactor was 2 m/sec it is not changed and kept as it is. Also high velocity in the shell
means correspondingly high velocity in tubes so the mean residence time will further
decrease from 0.02 sec to some lower value which is highly desirable because it will
reduce the amount of formic acid formed.
NOZZLE DESIGN
Velocity of gases = 2 m /sec
Volumetric flow rate of the mixture = 2.131 mol/sec per mol of formaldehyde.
= 33.37 litre/ sec mol = 71.11 * 10-3
m3
/sec
Calculation of diameter
∏*D2
* v / 4 = Volumetric flow rate of the mixture.
D = ( 71.11 * 10-3
* 14.265 * 4 / ( 2 * 3.142))0.5
= 80.45 cm.
Optimum diameter for nozzle:
dopt = 282 * G0.52
* ρ
-0.37
where G = flow rate in kg /sec
ρ=density of gas
on calculations dopt = 267 mm
choosing dia of 270 mm
Area to be compensated = 6 * 270 = 1620 mm2
Taking h2 = 1.5 * dn = 1.5 * 270 = 405 mm
Area of compensation provided by portion of nozzle outside reactor
= 2 * 202.5 (tn -1.75 - 3)
Area of compensation provided by portion of nozzle inside reactor
= 2 * 202.5 (tn – 3)
Area of compensation adjacent shell material = 270 * (6-1.75-3)

Formaldehyde 2014
Equating above areas of compensation to total area of compensation
2 * 202.5 (tn -1.75 - 3) + 2 * 202.5 (tn – 3) + 270 * (6-1.75-3) = 1620
on calculations tn = 4.86 mm ( taken as 5mm)
Similarly the design was done for the liquid water inlet. Whose diameter comes out to be 80
mm.
Support Design
(Reference Process Equipment Design – 2nd
Edition by M.V. Joshi Page 367).
Diameter of vessel = 1.2 m
Height of vessel = 6 m
thickness of vessel = 10 mm (shell)
For head
thickness = 6 mm
Straight portion of head = 0.5m
effective height of head = .4123m
density of carbon steel = PS = .286 lb/ Cu-1n
= .286  (12)3
lb/ cu – ft
= 494 .208 lb/ cu-ft
= 16.018  494 – 208
= 7916 K S /m3
Di = 1.2m D0 = 1.22 cm, H = 9.6 m
weight of shell =   si PHDD 
22
0
4

=      791636.7992.002.1
4
22


= 915 .3 kgf
weight of head =   ssi phDD 
22
0
4

  sprr 
3
1
3
0
3
2

     79165.0992.002.1
4
22



Formaldehyde 2014
     79160992.1072.
3
2 33
 
=63 Kgf
weight of liquid (EDC) filled in reactor
height of liquid
  HpDweight i  0
2
4
4

  4.088.410000.14992.0
4
32


= 4526 Kgf
 Total weight of Reactor = 915.3 + 63 + 4526
 5500 kgf (indudiny wt. of nozzle & other aceessories)
Total Weight = Weight of Vessel + Attachments + Catalyst Weight
Since this weight is much appreciable so lug support will not work here, so we go for
skirt support.
Skirt Support for vertical cylindrical vessel
Diameter of vessel = 0.992 m = 992 mm
Height of vessel = 7.36m = 7360 mm
Weight of vessel + attachments = 5000 kg.
Diameter of skirt (straight) = 992 mm
Height of skirt = 1.0 m
Wind pressure = 128.5 kg/m2
Skirt
Stress due to dead weight (draw diagram on page 367 M.V. Joshi)
ktkD
f
s0
w
0



 w dead wt. of vessel contents and attachments
D0k = Outside diameter of skirt

Formaldehyde 2014
tsk = thickness of skirt
2
0 /
73.17
2.99
5525
cmkg
ktkt
f
ss




Stress due to wind load
ktkD
Mw4
fwb
s
2
0

Z
H
PlwM  (for H  20m)
011lw DhkpP  up to 20m height
P1 = wind pressure for lower part of vessel
k1
= coefficient depending on the shape factor (0.7 for cylindrical surface)
D0 = outside diameter of vessel
2
H
Dhkpm 011
ktkD
2/HDhkp.4
f
s
2
0
011
wb


   
  kt
f
s
wb 2
100992.0
100
2
36.7
992.036.75.1287.04




2
/
27.31
cmkg
kts

Stress due to seismic load
  kt.Rok
WC
3
2
fsb
s
2


C = seismic coffecient = .08
W = total weight of vessel
Rok = outside radius of skirt
tsk = Skirt thickness
kt
bf
s
s 2
2
100992.0
552508.3/2





 




Formaldehyde 2014
2
/
03813.
cmkg
kts

Maximum tensile stress at bottom of skirt
    bfbforbfmaxf aswmaxt 
2
/
5.1377.1727.31
cmkg
ktktkt sss

Permissible tensile stress = 1400 kg /cm2
cmcmkts 00964.
1400
5.13

.0964 mm
Maximum compressive stress on skirt from equation
  absbwb fforfmax 
ktkttsk ss /09.48/77.17/27.31 
intpoyield
3
1
lepermisssibfs 
2
/666
3
2000
cmkg
cmcmkts 0721.0
666
09.48

Use a minimum thickness of 6 mm.
Skirt bearing plate
Assuming bolt circle diameter = Skirt diameter + 32.5 cm
=99.2 + 10.75 = 109.95 cm
Compressive stress between bearing plate and concrete foundation
Z
M
A
f ww
c 

 w = weight of vessel, contents & attachment
A = area of contact between bearing plate & foundation
Mw = bending moment due to wind
Z = Section modulus of area’
011e DhpkP 

Formaldehyde 2014
2
H
Dhpk
2
H
pM 011lww 
    22
2.9995.109
45525




fc
  
95.10932
2.9995.109
5.11992.05.1287.0
44





= 33.123 + .018 = 33.14 kg/cm2
which is less than the permissible value for concrete.
Maximum bending moment in bearing plate
2
bl
fM
2
cmax 
l = difference between outer radius of beaving plate and outer radil of skirt
b = circumferential length
  b
b
M 

 35.420
2
25.161837.3
max
2
Stress 22
max
.
35.42066
BB tb
b
tb
M
f


2
2
/
09.2522
cmkg
tB

Permissible stress in bending is 1575 kg/cm2
222
0166.0
1575
09.2522
cmEmtB 
cm
tB 16.
1.6 mm
Since the calculated thickness is less than 12 mm a steel rolled angle may be used as a
beaqring plate. Bolting chair need not be used.
FLANGE DESIGN:

Formaldehyde 2014
Design Pressure = 1.1 atm = 16.17 psia
Design temperature = 873 K
Flange material = ASTM A 201, Grade B
Bolting Material = ASTM A –193, Grade B –7
Gasket material = asbestos composition
Nozzle outside diameter = 0.280 m
Nozzle inside diameter = 0.270 m
Allowable stress of flange = 15000 psi
Allowable stress of bolting material =20000 psi
Calculation of Gasket width
do/di = ((y-pm)/(y-p(m+1)))0.5
Assuming a gasket thickness of 1/16 = 1.58 mm
y = 1600
m = 2.00
do/di = ((1600 – 14.7 –2)/(1600-14.7 *3)0.5
= 1.0052
Suppose di = 11.02
So do = 11.08
Minimum Gasket width = (11.08 – 11.02)/2 = 0.03
Which is too less, so we shall go for an 1/2 width gasket b =0.50
Mean gasket diameter = 11.02 + 0.50 = 11.52 
Calculation of bolt loads

Formaldehyde 2014
bo = n /2 = 0.50 /2 = 0.25 ; Now bo <=0.25
Load of seat Gasket
Hy = bGy
So, Wm2 = Hy = 0.5 * 3.14 * 11.52 * 1600
= 28938 lb
Load to keep joint tight under operation
Hp = 2bGmp
= 2 * 0.5 * 3.14 * 11.52 * 2.00 * 16.17
= 1170 lb
Load from internal pressure
H = G2
p/4 = 3.142 * 11.52^2 * 16.17 / 4
= 3600 lb
Total operating load
Wm1= H +Hp = 1170 + 3600
= 4770 lb
Wm2 > Wm1
So controlling load is Wm2 = 28938 lb
Calculation of minimum bolting area
Am1 = Wm2 / fb = 28938 / 20000 = 1.4469 in2
Calculation of optimum bolt size
Bolt size Root area Min no. of Bolts Actual Number

Formaldehyde 2014
¾ 0.302 4.79 8
So, Bolt circle diameter = 11.52 + 2* (1.415 * 0.00236 +9/8)
=16.92”
So,
B = 11.02” =0.280 m
A = 20.87” = 0.530m
C = 16.92” = 0.430 m
E =13/16” =0.8125” = 0.0206m
go = 0.236” = 0.006 m
R = 9/8 = 0.033 m
G = 3.425” = 0.087 m
t = 0.096 m
h = 0.175 m
Bolt diameter = 1/2 
No. of bolts = 4 (for symmetricity)
Flange O.D. = Bolt circle diameter + 2E
= 16.92 + 2 * 13/16
=16.92 + 1.625
=20.87”
MECHANICAL DESIGN OF ABSORBER
Calculate Di =2.56 m
Shell thickness

Formaldehyde 2014
Working Pressure = 1.3786  105
N/m2
Working Temperature = 300
C
Hydrostatic head = H g
here we consider  as density of water because we are using water as on absorbing
medium
Hydrostatic head = Hg
= 10.62x103
x 9.81
=104.82 103
N/m2
weight of packing approximately
= gHP
4
2



=   8.962.1056.3
4
609
2


= 63.44 KN/m2
Design Pressure =   23
/1044.3.182.104.86.13705.1 mN
= 320.71 KN/mm2
PJf2
PDi
t


Material Selection – Stainless Steel
for this material fall 300
C = 165  106
N/m2
Assuming Double welded butt joint with spot radiography J = 0.85
56
5
102071.3101652
56.3102071.3


t mm
= 4.1 mm
Ref. (Coulson & Richardson Volume – 6 , Page 641)
Minimum practical wall thickness (including corrosion allowance = 3 mm)
So, t = 8mm
 Thickness of wall = 5 mm (including corrosion allowance = 2 mm)
 mDo 008.256.3 
= 3.576 m
Torispherical Head design

Formaldehyde 2014
Do = 3.576 m
Let Ri = inside crown radius = Do = 3.576 m
ri = inside knucelete radius = .06 Di
= .06 * 3.56 = .2136 m
Assuming thickness t = 8mm
ro = outside knuclde radius = ri + t
= m2144.008.2136. 
Ro = Outside crown radius = r1 +1 = 3.576 + .008
= 3.584 m
ho = outside height of domed head











 
 200
2
D
R
2
D
RR o
o
o
oo (From geometry)
= 0.636 m
 
 
901.
584.34
576.3
4
22

oR
Do
685.
2
2144.*576.3
2
00

rD
hE = effective height of head = minimum of
















2
rD
R4/D
h
oo
o
2
o
o
 hE = .636 m
C = shape factor determined by graph
174.
576.3
636.

o
E
D
h
174.
576.3
008.

oD
t
from graph C = 1.40
Jf2
DP
t o
 fall 300
C = 165  106
J = 1.0

Formaldehyde 2014
Design Pressure 25
/103786.105.1 mNP 
25
/1044753.1 mN
0.1101652
4.156.3.1044753.1
6
5


t
= 2.186 mm
Minimum wall thickness including corrosion allowance (3mm)
ts = 5 mm
ro = outside kunckle radius = .2186 m
Ro = outside crown radius = .3581 m
* Since the diameter of the absorber is less, therefore we join head by welding to the
shell, there is no need of flange arrangement we can use double-welded lap joint for
this.
NOZZLE DESIGN
Moler flow rate = 2 mole/sec (approx)
Density of Water = 990 K/m3
So, Voumetric Flow Rate = Flow Rate of formaldehyde * molar flow rate of
water* mol. Wt. *density
= 14.265 * 2 *18 *990/1000
= 508.40 Kg/sec
dopt = 282 * G0.52
* ρ-0.37
= 282 * 508.40.52
* 990-0.37
= 318 mm
Taking nozzle dia. = 320 mm or 32 cm
Similarly Nozzle Dia for gas comes out to be 48 cm
Nozzle Reinforcement Design
Nozzle is provided on the head and it is welded there internal design pressure
= 3.2071  105
N/m2
= 2
4
5
/10/
10
102071.3
cmkg

= 3.2071 kg/cm2

Formaldehyde 2014
thickness of nozzle =
2071.3113002
35602071.3
2 




mm
PJf
PDi
tn
= 4.39 mm
No corrosion allowance, since the material is stainless stell.
 Actual thickness = 5 mm
Area to be compensated = d tRS
trs = thickness cale for shell
d = 5 cm (internal dia) + 8.4  10-3
(thickness) = 5 cm
= d  tRS = 320 5
= 1600 mm2
Area available for compensation As = d  ctt rss  (of shell)
=  3104.85320 3
 
= 640 mm2
Area available for compensation (external branch)
 CttH2A rnn1o 
let height of nozzle = 5 cm
tn = thickness of nozzle = 5 cm
trn = thickness of nozzle calculated
C = corrosion allowance
Ao = 2  320   2
320001068.5 mm
Area available for compensation from internal branch = 0
because the nozzle does not project inside the vessel.
2
38406403200 mmAA so 
Area to be compensated = 1600 mm2
=A
Since Ao + AS > A
This is satisfactory and no external compensation is required.
Reference Book
Support Design : Process Equipment Design (second editor) By M. V. Joshi
Since on absorber is not large, as result we can safely chose bracket or lug support for
vertical cylindrical vessels.

Formaldehyde 2014
Data : -
Diameter of vessel =3.56 m
Height of vessel = 10.62 m
Clearance from vessel both of foundation = 1.5m
Weight of vessel
Weight of vessel = weight of absorber + weight of pacing
weight of absorber =   s
2
i
2
o HDD
4


     750062.1056.3.576.3
4
22


= 7142.5 Kg
from Page 23-35 John H. Perry.
for Stainless steel 201 .inCu/lb28.s 
 
ftCu
bl
1228. 3


ftCu
bl
84.483


3
m/kg84.483018.16 
3
/14.7500 mkg
Mass of packing = b
2
i HD
4
2 


  kg60962.756.3
4
2


= 4532 kg.
Total weight of Tower
with contents = 7142.5 + 4532 + 500 Kg extra
= 12174.5 Kg
wind pressure = 128.5 kg/m2
Skirt
Stress due to dead weight

Formaldehyde 2014
ktkD
f
s0
w
0



 w dead wt. of vessel contents and attachments
D0k = Outside diameter of skirt
tsk = thickness of skirt
2
0 /
885.10
3560
5.12174
cmkg
ktkt
f
ss




Stress due to wind load
ktkD
Mw4
fwb
s
2
0

Z
H
PlwM  (for H  20m)
011lw DhkpP  up to 20m height
P1 = wind pressure for lower part of vessel
k1
= coefficient depending on the shape factor (0.7 for cylindrical surface)
D0 = outside diameter of vessel
2
H
Dhkpm 011
ktkD
2/HDhkp.4
f
s
2
0
011
wb


   
  kt
f
s
wb 2
356
100
2
62.10
56.362.105.1287.04



2
/
14.18
cmkg
kts

Stress due to seismic load
  kt.Rok
WC
3
2
fsb
s
2


C = seismic coefficient = .08
W = total weight of vessel
Rok = outside radius of skirt

Formaldehyde 2014
tsk = Skirt thickness
kt
bf
s
s 2
2
356
5.1217408.3/2









2
/
03813.
cmkg
kts

Maximum tensile stress at bottom of skirt
    bfbforbfmaxf aswmaxt 
2
/
255.7885.1014.18
cmkg
ktktkt sss

Permissible tensile stress = 1400 kg /cm2
cmcmkts 005282.
1400
255.7

.
=
05282 mm
Maximum compressive stress on skirt from equation
  absbwb fforfmax 
ktkttsk ss /025.29/14.18/885.10 
intpoyield
3
1
lepermisssibfs 
2
/666
3
2000
cmkg
cmcmkts 0721.0
666
025.29

Use a minimum thickness of 6 mm.
Skirt bearing plate

Formaldehyde 2014
Assuming bolt circle diameter = Skirt diameter + 10 % of skirt dia in cm
=356 + 35.6 cm = 391.6 cm
= 3.916 m
Compressive stress between bearing plate and concrete foundation
Z
M
A
f ww
c 

 w = weight of vessel, contents & attachment
A = area of contact between bearing plate & foundation
Mw = bending moment due to wind
Z = Section modulus of area’
011e DhpkP 
2
H
Dhpk
2
H
pM 011lww 
    22
3566.391
45.12174




fc
  
6.39132
3566.391
62.1056.35.1287.0
44





= 0.582 + .001 = 0.583 kg/cm2
which is less than the permissible value for concrete.
Maximum bending moment in bearing plate
2
bl
fM
2
cmax 
l = difference between outer radius of bearing plate and outer radii of skirt
b = circumferential length
  b
b
M 

 98.92
2
86.17583.0
max
2
Stress : 22
max
.
98.9266
BB tb
b
tb
M
f


2
2
/
8.557
cmkg
tB


Formaldehyde 2014
Permissible stress in bending is 1575 kg/cm2
222
3541.0
1575
8.557
cmEmtB 
cmtB 59. = 5.9 mm
Since the calculated thickness is less than 12 mm steel rolled angle may be used as a bearing
plate. Bolting chair need not be used.

Formaldehyde 2014
EFFLUENT TREATMENT
WASTE CHARACTERSTICS
The major waste stream from the process is the "formaldehyde in water" and
formaldehyde vapors released into atmosphere. Beside formic acid, Carbon-mono-oxide
etc., which need to be treated before disposal. Carbon-mono-oxide and other gases are
in low concentration, so they are not treated as such but released at high elevation in
atmosphere.
Formalin is a highly toxic gas, and strict precautions are necessary to minimize risk
to workers and possible released during its handling. Major sources of fugitive air
emissions of chlorine and hydrogen are vents, seals, and transfer operations. Acid
and caustic wastewaters are generated in both the process and the materials
recovery stages.
Scrubber systems should be installed to control gas effluent emissions from condensers
and at storage and transfer points for liquid chlorine. Sulfuric acid used for drying
chlorine should be neutralized before discharge.
KEY ISSUES
The following summarizes the key production and control practices that will lead to
compliance with emissions guidelines.
1) Give preference to the effluent gases.
2) Adopt the following pollution prevention measures to minimize emissions.
3) Use scrubbers at the absorber to minimize the off-gases from it.
4) Recycling of water in air washer should be treated.
5) Recycling of dust containing water should be from suitable pumps.
In the effluent treatment plant, the formic acid going along with the water is passed
through an ion exchange bed. A sample design fo a deionizer for the treatment of formic
acid from the formalin stream is given below. A similar treatment can be devised for
outlet water stream.

Formaldehyde 2014
Secondly, the settling tank can be designed for the treatment of rundown water from the
air washer.
DEIONIZER
Process design consideration
For ion exchange system sizing, the quantity of liquid to be processed in a period
of time must be determined. The processing rate if often expressed in gallons per
day or pounds per day.
Processing rate = quantity to be processed / time period minus regeneration time
Equipment must be sized such that the service time is sufficient to allow a unit in
regeneration to be completed prior to the exhaustion of the usable capacity of the
unit in service. The service time of a single unit in a multiple unit system is usually
designed for a service time, which exceeds the sum of the regeneration time
required for all of all the units in service. Having the required feed processing rate
per fixed-bed ion exchanger and the required length of the service period, the
exchanger or adsorption load to each unit for a service period can be calculated.
For continuous ion exchange equipment, the load is calculated on the basis of
exchange load per unit time. Generally, the capacities of an ion-exchange material
to remove a given component are determined experimentally. But the data is
available on common materials.
Variables on which the amount of ion-exchange bed required depends are
conc. of the component to be removed, process flow contact rate, regenerant
chemical conc., etc. Ion-exchange capacities are affected by the rate of mass
transfer between the process fluid and ion-exchange resin.

Formaldehyde 2014
REQUIREMENT FOR EQUIPMENT DESIGN
TANKS AND VESSELS
Typically, a tank diameter which will allow service operation at flows that will
exceed 2 gpm/ft2
of tank area and not exceed 12 gpm/ft2
are acceptable. Once
the vessel diameter is determined, the ion-exchange media bed depth can be
calculated (media volume divided by area = bed depth). The resin bed depth in a
fixed-bed-ion-exchange unit usually should exceed 30in. and be limited to a
maximum depth of 96 in.. High flows per unit area and deep ion-exchange resin
depths may result in high-pressure drops. Pressure losses across a resin bed are
normally limited to 10-20 lb/in2
. Large pressure losses can, in combination with
exchange media volume changes (result from ionic or osmotic changes), causes
physical damage to the exchange media, the exchanger, and the internals of the
exchanger.
The chemicals that are used to regenerate the resins or the nature of the liquid
being processed dictate the use of interior coating or linings in an ion-exchanger
tank.
PIPINGS AND VALVES
These equipments are commonly constructed with PVC, stainless steel, or lined
carbon steel flanged piping. Selection of valves suitable for the intended service is
especially important. Lined carbon-steel pipes are generally used on large
equipments.
EXCHANGE MEDIA SUPPORT
Several design, like flat false bottom designs, dished tank bottom with graded
gravel media support beds, are available for supporting the ion-exchange resin.
FLOW DISTRIBUTION
For efficient working of ion-exchange resins, plug flow is generally preferred. Well-
distributed liquid flow distributors are required for that.

Formaldehyde 2014
DESIGN
Formalin flow rate = 300 tons/day
Conc. of formic acid (max. possible) = 0.04%
Formic acid (in Kg/day) = (0.04/100) * 300 *1000
= 120 Kg/day
Reaction occuring is:
R(OH)2 + 2HCOOH R(COOH)2 + 2H2O
Density of 37 wt.% formaldehyde solution:
d= 1.000 + 0.003*W
d= 1.000 + 0.003*37
d= 1.111
d= 1111 Kg/m3
Volume of solution = weight/density
Volume of solution = 300*1000/1111
volume of solution = 270.03 m3
/day
conc. of formaldehyde = 120Kg/day
270.03 m3
/day
= 0.444 gm/lt
= 444 mg/lt
Eq. Wt. Of HCOOH =46/1(mol.wt./bascity)
=46
meq/lt of HCOOH = 444 mg/lt / 46
= 9.65
Total meq treated per day = 9.65 * 270.03 * 103
= 2605.79 eq/day
Resin Requirement:
Assumed 6-day operation cycle for the specific resin
Treating power of resin = 70 eq/ft3

Formaldehyde 2014
Resin reqd. =2605.79 eq./day* 6
day/cycle
70 eq./ft3
= 223.35ft3
of
resin/day
Choosing column diameter = 3 ft. = 0.0762 m
Cross-section area = 3.142*32
/4 = 7.07 ft2
Depth = volume/cross-sectional area
= 223.35/7.07 = 31.6 ft = 9.48 m
50% of free space is kept for bed expansion for backwashing and cleaning.
So, the height of reqd. column is 1.5 * 9.48 =14.22 m
Height is quite high. So, using 2 columns of 7.11 m height each.
Each containing =9.48/2 = 4.74 m
Free space = 7.11 – 4.74= 2.37 m
Regenrant Reqd.
Regenrant used is 10% solution of NaOH
Regenrant requirement is 4.7 lb of NaOH/ ft3
of resin
So NaOH reqd. = 4.7 lb/ft3
*223.35 ft3
/cycle
= 1049.745 lb/cycle = 476.58 Kg/cycle
Requirement of 10% solution
= 476.58*100/10
= 4765.8 Kg/cycle
Water requirement
Water requirement =100 gallon/ft3
of resin
Water requirement = 100gallon/ft3
of resin* 223.35 ft3
/cycle
= 22335 gallon/cycle
= 84.55 m3
/day

Formaldehyde 2014
SAFETY POLICY
EFFECITVE SAFETY AND LOSS PREVENTION IS ESSENTIAL FOR A COMPANY’S
PROSPERITY
Hazards in the chemical industry are much more than in any other industry.
Besides mechanical and electrical hazards, chances of fire explosion, inhalation
of toxic gases, handling of corrosive and poisonous substances are encouraged in
chemical industry. Thus it is important that the employee should recognize safety
and fire hazards in the manufacture of soda ash.
Objectives of industrial safety program are: -
a) To lessen human sufferings.
b) To prevent damage to plant and machinery.
c) To reduce the amount of time lost due to accidents.
d) To hold the expense of workman compensation to minimum.
GENERAL SAFETY
1) Alternate means of escape should be provided in the plant area.
2) Gloves and goggles should be used while sampling or welding the
equipment.
3) Going without helmet, gloves and rubber bolts near the leaking
equipment should be avoided.
ELECTRICAL HAZARDS:
Accidents attributed to electrical hazards are:-
1) Shocks by A.C. and burns by D.C. due to poor indication and protection
from high voltage.
2) Faulty and poor wiring.
3) Static electricity discharges.

Formaldehyde 2014
4) Fires from sparking near inflammable material.
PROCESS UTILITIES
Process utilities are a major necessity for any chemical plant. The following are
usually considered utilities although in some companies one or more are treated
under other categories on the cost sheet. The utility cost for the whole plant (from
coat estimation sheet) is Rs.1.97412×108
Steam, Cooling water, Deionized water, Electric power, Refrigeration ,
Compressed air , Instrument air, Effluent treatment. Their effect on the cost of
the production will naturally depend on the process involved Occasionally the
costing of the utilities will be intricate because utilities require other utilities for
their own manufacture.
STEAM
A steam generation unit should be present which is a source of steam where ever
it is required .It is measured in thousands of pounds or for small boilers it may be
measured in boiler horse power(33,749 BTU/hr).A pound of steam generated may
have 1200 to1600BTU/lb.Most plants use several stem pressure levels . In many
plants waste heat boilers are additional source of steam at intermediate pressure
levels .
Steam is available at following rating in our plant
Pressure ----------- 400 Kpa
Temperature-------- 204.44 o
C
Latent heat -------------826 Btu/lb or 1920 Kj/kg
WATER
Water requirements fall under three categories, cooling, process, and
miscellaneous such as washing or drinking. For cooling purpose it is usually
uneconomical and occasionally violation of conservation laws to use to use a

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